Modern aircraft, such as an F-15E aircraft manufactured by the assignee of the present invention, and the P-3, the S-3 and the F-16 aircraft manufactured by Lockheed Aeronautical Systems Company, are adapted to carry stores. These stores can, for example, include missiles, such as the Joint Direct Attack Munition (JDAM), the Walleye missile, the Standoff Land Attack missile (SLAM), the SLAM-ER missile, the Harpoon missile, and the Maverick missile. A missile is generally mounted to the wing of a host aircraft, typically via disconnectable pylons, such that the aircraft can carry the missile to the vicinity of the target destination prior to its deployment.
Prior to uploading the store to the aircraft pylon, the aircraft and its provisioning for the store must be tested and certified to be within the specifications for acceptable store launching operation. To perform these preinstallation certification tests, ground support test equipment are deployed with the aircraft for the purpose of testing the aircraft via the Pylon Store Interface Cable Connector. For example the ground support test set for the P-3 aircraft includes the AWM 96 Test Set which has the capability of testing the electrical performance of every circuit in the aircraft-to-store interface cable. This includes testing for proper voltage, frequency, power, timing, and wiring impedance. Discrete signal conductors are tested to insure adequate voltage magnitude and timing. Communication signals are tested for bi-directional transmission and proper protocol. Additional tests verify the ability of the aircraft to provide safety logic and assure that weapon launch and abort functions are operating correctly.
To certify the readiness of the aircraft for weapon store upload and interconnections, the ground test equipment must be precertified as operational. This is assured through proper design and configuration control as well as periodic testing of the ground support equipment itself. Once certified, the ground support equipment can only be changed using costly formal change programs involving lengthy schedule time.
Aircraft, such as the P-3, for example, can be equipped to carry additional weapons, not included in the stores inventory, by adding functions in cable modules and in the umbilical cable wiring between the weapon store and the aircraft pylon connector. Adding functions to the aircraft wiring and weapon umbilical cable allows the aircraft and its existing weapon system to remain unchanged while expanding the weapon store inventory to include additional store types. An example of this is the addition of the SLAM-ER weapon to the P-3 aircraft equipped with the Harpoon weapon system. The SLAM-ER weapon requires special power characteristics and timing not included in the Harpoon weapon system. To achieve the SLAM-ER power compatibility with the P-3 aircraft and its Harpoon weapon system, a special umbilical cable that includes power-switching relays may be added between the aircraft pylon connector and the SLAM-ER weapon store. This cable allows the existing Harpoon weapon system control panel switch functions in the P-3 aircraft to use the Harpoon power sources and logic functions to initiate the power sequences required by MIL-STD 1760 for the SLAM-ER missile launch cycle. However, prior to uploading a SLAM-ER weapon onto the aircraft pylon, the aircraft and its Harpoon weapon system with the SLAM-ER weapon umbilical cable must be certified for the SLAM-ER weapon store.
The test equipment used to certify the P-3 aircraft and Harpoon Weapon system for MIL-STD 1760 SLAM-ER Weapon launching is the AWM 96 Ground Support Test Set. This test set connects directly to the aircraft-to-missile umbilical connector and either certifies the aircraft and its weapon control system to be within specifications for launching a weapon, or rejects the aircraft as non-serviceable. The AWM 96 Test Set includes tests of the source voltages and source impedances required for the MIL-STD 1760 weapon, but the “Go/No-Go” limits are inadequate for the SLAM-ER. That is, the AWM 96 Test Set could certify the aircraft and SLAM-ER weapon system as in specification or a “Go” condition with insufficient source voltage and/or too high of source impedance to successfully launch a SLAM-ER weapon store. For example, the SLAM-ER weapon requires the aircraft to supply DC # 2 open circuit voltage of 26.5 volts and a source impedance of 0.75 ohms, whereas the existing AWM 96 Test Set accepts open circuit voltage of 22 volts and 1.0 ohm source impedance as an acceptable or “Go” test result. The lower voltage and higher impedance allowed by the test set measurement would not assure adequate power delivered to the weapon loads, and therefore would erroneously certify the aircraft for SLAM-ER weapon upload.